text: /* See LICENSE file for copyright and license details. */
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  #include <X11/Xlib.h>
  #include <X11/Xft/Xft.h>
  
  #include "drw.h"
  #include "util.h"
  
  #define UTF_INVALID 0xFFFD
  #define UTF_SIZ     4
  
  static const unsigned char utfbyte[UTF_SIZ + 1] = {0x80,    0, 0xC0, 0xE0, 0xF0};
  static const unsigned char utfmask[UTF_SIZ + 1] = {0xC0, 0x80, 0xE0, 0xF0, 0xF8};
  static const long utfmin[UTF_SIZ + 1] = {       0,    0,  0x80,  0x800,  0x10000};
  static const long utfmax[UTF_SIZ + 1] = {0x10FFFF, 0x7F, 0x7FF, 0xFFFF, 0x10FFFF};
  
  static long
  utf8decodebyte(const char c, size_t *i)
  {
  	for (*i = 0; *i < (UTF_SIZ + 1); ++(*i))
  		if (((unsigned char)c & utfmask[*i]) == utfbyte[*i])
  			return (unsigned char)c & ~utfmask[*i];
  	return 0;
  }
  
  static size_t
  utf8validate(long *u, size_t i)
  {
  	if (!BETWEEN(*u, utfmin[i], utfmax[i]) || BETWEEN(*u, 0xD800, 0xDFFF))
  		*u = UTF_INVALID;
  	for (i = 1; *u > utfmax[i]; ++i)
  		;
  	return i;
  }
  
  static size_t
  utf8decode(const char *c, long *u, size_t clen)
  {
  	size_t i, j, len, type;
  	long udecoded;
  
  	*u = UTF_INVALID;
  	if (!clen)
  		return 0;
  	udecoded = utf8decodebyte(c[0], &len);
  	if (!BETWEEN(len, 1, UTF_SIZ))
  		return 1;
  	for (i = 1, j = 1; i < clen && j < len; ++i, ++j) {
  		udecoded = (udecoded << 6) | utf8decodebyte(c[i], &type);
  		if (type)
  			return j;
  	}
  	if (j < len)
  		return 0;
  	*u = udecoded;
  	utf8validate(u, len);
  
  	return len;
  }
  
  Drw *
  drw_create(Display *dpy, int screen, Window root, unsigned int w, unsigned int h)
  {
  	Drw *drw = ecalloc(1, sizeof(Drw));
  
  	drw->dpy = dpy;
  	drw->screen = screen;
  	drw->root = root;
  	drw->w = w;
  	drw->h = h;
  	drw->drawable = XCreatePixmap(dpy, root, w, h, DefaultDepth(dpy, screen));
  	drw->gc = XCreateGC(dpy, root, 0, NULL);
  	XSetLineAttributes(dpy, drw->gc, 1, LineSolid, CapButt, JoinMiter);
  
  	return drw;
  }
  
  void
  drw_resize(Drw *drw, unsigned int w, unsigned int h)
  {
  	if (!drw)
  		return;
  
  	drw->w = w;
  	drw->h = h;
  	if (drw->drawable)
  		XFreePixmap(drw->dpy, drw->drawable);
  	drw->drawable = XCreatePixmap(drw->dpy, drw->root, w, h, DefaultDepth(drw->dpy, drw->screen));
  }
  
  void
  drw_free(Drw *drw)
  {
  	XFreePixmap(drw->dpy, drw->drawable);
  	XFreeGC(drw->dpy, drw->gc);
  	free(drw);
  }
  
  /* This function is an implementation detail. Library users should use
   * drw_fontset_create instead.
   */
  static Fnt *
  xfont_create(Drw *drw, const char *fontname, FcPattern *fontpattern)
  {
  	Fnt *font;
  	XftFont *xfont = NULL;
  	FcPattern *pattern = NULL;
  
  	if (fontname) {
  		/* Using the pattern found at font->xfont->pattern does not yield the
  		 * same substitution results as using the pattern returned by
  		 * FcNameParse; using the latter results in the desired fallback
  		 * behaviour whereas the former just results in missing-character
  		 * rectangles being drawn, at least with some fonts. */
  		if (!(xfont = XftFontOpenName(drw->dpy, drw->screen, fontname))) {
  			fprintf(stderr, "error, cannot load font from name: '%s'\n", fontname);
  			return NULL;
  		}
  		if (!(pattern = FcNameParse((FcChar8 *) fontname))) {
  			fprintf(stderr, "error, cannot parse font name to pattern: '%s'\n", fontname);
  			XftFontClose(drw->dpy, xfont);
  			return NULL;
  		}
  	} else if (fontpattern) {
  		if (!(xfont = XftFontOpenPattern(drw->dpy, fontpattern))) {
  			fprintf(stderr, "error, cannot load font from pattern.\n");
  			return NULL;
  		}
  	} else {
  		die("no font specified.");
  	}
  
  	/* Do not allow using color fonts. This is a workaround for a BadLength
  	 * error from Xft with color glyphs. Modelled on the Xterm workaround. See
  	 * https://bugzilla.redhat.com/show_bug.cgi?id=1498269
  	 * https://lists.suckless.org/dev/1701/30932.html
  	 * https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=916349
  	 * and lots more all over the internet.
  	 */
  	/*
  	FcBool iscol;
  	if(FcPatternGetBool(xfont->pattern, FC_COLOR, 0, &iscol) == FcResultMatch && iscol) {
  		XftFontClose(drw->dpy, xfont);
  		return NULL;
  	}
  	*/
  
  	font = ecalloc(1, sizeof(Fnt));
  	font->xfont = xfont;
  	font->pattern = pattern;
  	font->h = xfont->ascent + xfont->descent;
  	font->dpy = drw->dpy;
  
  	return font;
  }
  
  static void
  xfont_free(Fnt *font)
  {
  	if (!font)
  		return;
  	if (font->pattern)
  		FcPatternDestroy(font->pattern);
  	XftFontClose(font->dpy, font->xfont);
  	free(font);
  }
  
  Fnt*
  drw_fontset_create(Drw* drw, const char *fonts[], size_t fontcount)
  {
  	Fnt *cur, *ret = NULL;
  	size_t i;
  
  	if (!drw || !fonts)
  		return NULL;
  
  	for (i = 1; i <= fontcount; i++) {
  		if ((cur = xfont_create(drw, fonts[fontcount - i], NULL))) {
  			cur->next = ret;
  			ret = cur;
  		}
  	}
  	return (drw->fonts = ret);
  }
  
  void
  drw_fontset_free(Fnt *font)
  {
  	if (font) {
  		drw_fontset_free(font->next);
  		xfont_free(font);
  	}
  }
  
  void
  drw_clr_create(Drw *drw, Clr *dest, const char *clrname)
  {
  	if (!drw || !dest || !clrname)
  		return;
  
  	if (!XftColorAllocName(drw->dpy, DefaultVisual(drw->dpy, drw->screen),
  	                       DefaultColormap(drw->dpy, drw->screen),
  	                       clrname, dest))
  		die("error, cannot allocate color '%s'", clrname);
  }
  
  /* Wrapper to create color schemes. The caller has to call free(3) on the
   * returned color scheme when done using it. */
  Clr *
  drw_scm_create(Drw *drw, const char *clrnames[], size_t clrcount)
  {
  	size_t i;
  	Clr *ret;
  
  	/* need at least two colors for a scheme */
  	if (!drw || !clrnames || clrcount < 2 || !(ret = ecalloc(clrcount, sizeof(XftColor))))
  		return NULL;
  
  	for (i = 0; i < clrcount; i++)
  		drw_clr_create(drw, &ret[i], clrnames[i]);
  	return ret;
  }
  
  void
  drw_setfontset(Drw *drw, Fnt *set)
  {
  	if (drw)
  		drw->fonts = set;
  }
  
  void
  drw_setscheme(Drw *drw, Clr *scm)
  {
  	if (drw)
  		drw->scheme = scm;
  }
  
  void
  drw_rect(Drw *drw, int x, int y, unsigned int w, unsigned int h, int filled, int invert)
  {
  	if (!drw || !drw->scheme)
  		return;
  	XSetForeground(drw->dpy, drw->gc, invert ? drw->scheme[ColBg].pixel : drw->scheme[ColFg].pixel);
  	if (filled)
  		XFillRectangle(drw->dpy, drw->drawable, drw->gc, x, y, w, h);
  	else
  		XDrawRectangle(drw->dpy, drw->drawable, drw->gc, x, y, w - 1, h - 1);
  }
  
  int
  drw_text(Drw *drw, int x, int y, unsigned int w, unsigned int h, unsigned int lpad, const char *text, int invert)
  {
  	char buf[1024];
  	int ty;
  	unsigned int ew;
  	XftDraw *d = NULL;
  	Fnt *usedfont, *curfont, *nextfont;
  	size_t i, len;
  	int utf8strlen, utf8charlen, render = x || y || w || h;
  	long utf8codepoint = 0;
  	const char *utf8str;
  	FcCharSet *fccharset;
  	FcPattern *fcpattern;
  	FcPattern *match;
  	XftResult result;
  	int charexists = 0;
  
  	if (!drw || (render && !drw->scheme) || !text || !drw->fonts)
  		return 0;
  
  	if (!render) {
  		w = ~w;
  	} else {
  		XSetForeground(drw->dpy, drw->gc, drw->scheme[invert ? ColFg : ColBg].pixel);
  		XFillRectangle(drw->dpy, drw->drawable, drw->gc, x, y, w, h);
  		d = XftDrawCreate(drw->dpy, drw->drawable,
  		                  DefaultVisual(drw->dpy, drw->screen),
  		                  DefaultColormap(drw->dpy, drw->screen));
  		x += lpad;
  		w -= lpad;
  	}
  
  	usedfont = drw->fonts;
  	while (1) {
  		utf8strlen = 0;
  		utf8str = text;
  		nextfont = NULL;
  		while (*text) {
  			utf8charlen = utf8decode(text, &utf8codepoint, UTF_SIZ);
  			for (curfont = drw->fonts; curfont; curfont = curfont->next) {
  				charexists = charexists || XftCharExists(drw->dpy, curfont->xfont, utf8codepoint);
  				if (charexists) {
  					if (curfont == usedfont) {
  						utf8strlen += utf8charlen;
  						text += utf8charlen;
  					} else {
  						nextfont = curfont;
  					}
  					break;
  				}
  			}
  
  			if (!charexists || nextfont)
  				break;
  			else
  				charexists = 0;
  		}
  
  		if (utf8strlen) {
  			drw_font_getexts(usedfont, utf8str, utf8strlen, &ew, NULL);
  			/* shorten text if necessary */
  			for (len = MIN(utf8strlen, sizeof(buf) - 1); len && ew > w; len--)
  				drw_font_getexts(usedfont, utf8str, len, &ew, NULL);
  
  			if (len) {
  				memcpy(buf, utf8str, len);
  				buf[len] = '\0';
  				if (len < utf8strlen)
  					for (i = len; i && i > len - 3; buf[--i] = '.')
  						; /* NOP */
  
  				if (render) {
  					ty = y + (h - usedfont->h) / 2 + usedfont->xfont->ascent;
  					XftDrawStringUtf8(d, &drw->scheme[invert ? ColBg : ColFg],
  					                  usedfont->xfont, x, ty, (XftChar8 *)buf, len);
  				}
  				x += ew;
  				w -= ew;
  			}
  		}
  
  		if (!*text) {
  			break;
  		} else if (nextfont) {
  			charexists = 0;
  			usedfont = nextfont;
  		} else {
  			/* Regardless of whether or not a fallback font is found, the
  			 * character must be drawn. */
  			charexists = 1;
  
  			fccharset = FcCharSetCreate();
  			FcCharSetAddChar(fccharset, utf8codepoint);
  
  			if (!drw->fonts->pattern) {
  				/* Refer to the comment in xfont_create for more information. */
  				die("the first font in the cache must be loaded from a font string.");
  			}
  
  			fcpattern = FcPatternDuplicate(drw->fonts->pattern);
  			FcPatternAddCharSet(fcpattern, FC_CHARSET, fccharset);
  			FcPatternAddBool(fcpattern, FC_SCALABLE, FcTrue);
  			FcPatternAddBool(fcpattern, FC_COLOR, FcFalse);
  
  			FcConfigSubstitute(NULL, fcpattern, FcMatchPattern);
  			FcDefaultSubstitute(fcpattern);
  			match = XftFontMatch(drw->dpy, drw->screen, fcpattern, &result);
  
  			FcCharSetDestroy(fccharset);
  			FcPatternDestroy(fcpattern);
  
  			if (match) {
  				usedfont = xfont_create(drw, NULL, match);
  				if (usedfont && XftCharExists(drw->dpy, usedfont->xfont, utf8codepoint)) {
  					for (curfont = drw->fonts; curfont->next; curfont = curfont->next)
  						; /* NOP */
  					curfont->next = usedfont;
  				} else {
  					xfont_free(usedfont);
  					usedfont = drw->fonts;
  				}
  			}
  		}
  	}
  	if (d)
  		XftDrawDestroy(d);
  
  	return x + (render ? w : 0);
  }
  
  void
  drw_map(Drw *drw, Window win, int x, int y, unsigned int w, unsigned int h)
  {
  	if (!drw)
  		return;
  
  	XCopyArea(drw->dpy, drw->drawable, win, drw->gc, x, y, w, h, x, y);
  	XSync(drw->dpy, False);
  }
  
  unsigned int
  drw_fontset_getwidth(Drw *drw, const char *text)
  {
  	if (!drw || !drw->fonts || !text)
  		return 0;
  	return drw_text(drw, 0, 0, 0, 0, 0, text, 0);
  }
  
  void
  drw_font_getexts(Fnt *font, const char *text, unsigned int len, unsigned int *w, unsigned int *h)
  {
  	XGlyphInfo ext;
  
  	if (!font || !text)
  		return;
  
  	XftTextExtentsUtf8(font->dpy, font->xfont, (XftChar8 *)text, len, &ext);
  	if (w)
  		*w = ext.xOff;
  	if (h)
  		*h = font->h;
  }
  
  Cur *
  drw_cur_create(Drw *drw, int shape)
  {
  	Cur *cur;
  
  	if (!drw || !(cur = ecalloc(1, sizeof(Cur))))
  		return NULL;
  
  	cur->cursor = XCreateFontCursor(drw->dpy, shape);
  
  	return cur;
  }
  
  void
  drw_cur_free(Drw *drw, Cur *cursor)
  {
  	if (!cursor)
  		return;
  
  	XFreeCursor(drw->dpy, cursor->cursor);
  	free(cursor);
  }
  